The Radio facsimile System As used In this manual, “radio facsimile transmission” means sending a facsimile signal by radio. We have included the principles of facsimile and radio facsimile here for your reference.
Facsimile Principles Basically, what a facsimile System does is to convert visual Information into an electronic signal at the senders end, transmit this signal electronically, and reconvert to visual form at tha recipients end. Sender Recipient Ringling Electronic signal Electronic signal Hard copy Transmission Al the sender’s aids, the original is broken up Into & fine rid, and the darkness information i3 read off one line at & time and transmitted to the recipient.
Reception At the receiving end, a piece of recording peer is wrapped round 4 drum the same size as the transmission drum, and the drum is notated at the same speed. A needs s In ‘contact with the drum with the signal current applied 1o it, and e darkness of the image produced vales with the amount of current 10 reproduce the original image, One Lina is reproduced with sate rotation of the drum.
Facsimile Principles Vertical/Horizontal Ratio — “Index of Cooperation” The width of the reproduced frame is determined by the diameter of the drum, while the height is determined by the shirt density, or how many scanning fines are in each millimeter.
Radio facsimile Modulation When graphic information is electronically transmitted using radio facsimile, the black and white areas are represented by two different radio frequencies. When receiving, assuming A is the published frequency, since this Is only the center frequency before frequency shifting, (A— 400z is the frequency for black, and is the frequency Tor white. (When a photograph s transmitted, intermediate frequencies are alas used 10 represent halftones.
Radio facsimile Transmission of Weather Chart A wide variety of weather charts are transmitted around the world, directed at shipping, airplanes, and other users. The broadcasts include surface analyses (temperature, wind direction, wind speed and atmospheric pressure charts, efface, upper-air analyses (satellite photos, etc), and sea conditions charts {wave heights, etc). Both present conditions snd predictions are broadcast. World Weather Radio facsimile Stations ST g D“ 255 San cars ..
Radio facsimile Transmission of Weather Charles Radioactive Weather Chart Examples Weather Satellite GMS Cloud Photo (Station; JMH, Heading: GMS picture} Open Sea Wave Analysis {Station: JMH, Heading: AWN)
When Clear Reception Cannot Be Obtained —— Cause and Cure Even when reception and facsimile reproduction satisfying are correct, it may sometimes bs difficult to abstain clear reception. Followings ars some examples of certain problems that can arise and how 1o solve tho.
en Clear Reception Cannot Be Obtained A: Streaking Cause: Fading Interference The signal transmitted from e broadcast station arrives by two different paths. The combined signals resit in nose. This s called fading interference. Cure: Ba cause short-wave signals ars strongly affected by the ionosphere, it is impossible to completely eliminate this problem, but using a eighty directional baa antenna (one that receives mare strongly from one particular direction) will improve reception in many cases.
C: Severe stripes appear or chart is difficult to read Cause: Radio interference Cure: An interfering station is transmitting near the reception frequency, or a source of dialectical interference is near the antenna. Naturally, eliminating the source of interference Is he best method, but the use of 2 good beam antenna can make ar improvement in many cases.
When Clear Reception Cannes Be Obtained—Cause and Cure E: A pattern of stripes or dots appear Gauss: Electrical interference from a car's ignition system ot an electric motor, eic. Cure: Locate the antenna as far as possible firm the source of Interference. If the noise 1s not toa bad, it can be reduced by adjusting the printing contrast {see page 44 in the “Operating Instructions”).
Weather Chart Radio facsimile Frequency List Most broadcast stations transmit simultaneously on several frequencies, so choose the frequency that provides best reception depending on the season, time of day, and location, 2
Weather Chart Radio facsimile Frequency List Station Frequency Transmission speed (pm) Index of Cooperation 9225 Kz 7305 kHz Tokyo 1 | Hook 2 760 18697 KHz 15200 Kz (Some broadcasts are 603 panda 22770 iz 2365 kHz 5405 kHz. Tokyo 2 9438 whiz 120 B76(H} 14692.5 Kz 18130 kHz 5525 kHz 8120 khz People’s Republic of China | 10116 kHz* 120 56H) 14965 kHz 18235 kHz. 45987 KRz 7475 kHz Khabarovsk 923 kHz €0, 90, 120 576(H) 14737 iz {Some broadcasts are 2680)) 19275 k2.
Station Frequency Transmission speed {rpm) index of Cooperation United Kingdom 26185 xHz 4782 kHz 9200 kHz 14436 kHz. 18261 whiz 5764} (Sue broadcasts are 268600 Madrigal 2850 kHz 68185 kHz 10250 kiz 120 (Some broadcasts are 60} B76H) Spain AT Kz 5206 kHz 7826 kHz 8100 kHz 12184 khz 12603 kHz 159415 kid 5760 Sweden 4037.5 Kz, B901 kHz 80715 krill 76 Turkey 5790 k2. E76(H) These frequencies are those of June 1887 and are subject to change.
